Aspects of the invention can relate to a projector that projects an image and a polarization member used in a projector or the like due to its polarization adjustment function. In a related art projector of a type in which a liquid crystal light valve is incorporated, polarization elements can be normally disposed on the both sides of the light incident surface and the light exiting surface of a liquid crystal panel to adjust a polarization state. Light absorption type polarizers are often used as the polarization elements. The light absorption type polarizers, however, have a problem in that resistance to light and heat is poor and the life is short.
In order to solve this problem, resistance to light and heat of the polarization elements can be improved using light refection type polarizers, such as structured birefringent polarizers. See, for example, WO01 055778. In order to prevent reflected lights that are reflected on the reflection type polarizer disposed on the light exiting side, namely, unwanted lights, from returning to the light incident side, and thereby causing a malfunction, the above document also discloses a prism that satisfies a condition for the reflected lights from the polarizer to undergo total reflection on the light incident surface.
However, when lights are reflected twice or more inside the prism, the optical paths of reflected lights become more complicated. For example, it is necessary to consider multi-reflected lights, which are lights reflected on the polarizer on the light exiting side again after they undergo total reflection on the light incident surface of the prism. In this case, of incident lights entering into the prism via the incident surface, for example, for those entering at points far from a light discharge region, there is a possibility that multi-reflected lights are not discharged from the light discharge region, and eventually return toward the light incident surface. A countermeasure to avoid this inconvenience, however, raises another problem that an effective region for incident lights has to be made narrower with respect to the entire prism at the time of incidence.